UC Irvine

Communication between heterogeneous populations of cells within a tissue dictate the overall function of the tissue and is often disregulated in disease states. This crosstalk can be quite complex and difficult to study. We investigate heterotypic cell-cell signaling using a microfabricated co-culture system that allows us to easily purify each population following co-culture for independent analysis and to rapidly manipulate the populations so that even very brief co-cultures can be precisely achieved. The devices are also designed so that the populations can be co-cultured in close proximity for maximum exchange to occur. We have previously used this platform to study the maintenance or differentiation of various types of stem and progenitor cells. In this current work we use the co-culture system to develop a high-throughput screening technique for short-range paracrine interactions. The platform was also utilized in conjunction with conventional tools to study the effects of tumor-stromal interactions on fibroblast migration. We found that colon cancer cells induce colon fibroblast migration through a mechanism involving canonical WNT signaling and urokinase-type plasminogen activator (uPA) induction. These findings are crucial to understanding how tumor cells recruit stromal cells into the tumor microenvironment to promote cancer progression. In addition to making the short-range screening platform, we also created an experimental model for morphogen-dependent border formation in the developing telencephalon using the comb system and began to study the effects of BMP and FGF signaling interactions on dissociated cortical precursor cells (dCPC). Finally, we developed a method of maintaining mouse embryonic stem cells (mESC) that facilates easy extration of pure mESCs populations from culture with feeder cells. In doing so, we showed that maintenance of stem cell markers in feeder-dependent mESCs may not require direct contact with feeders, as was previously thought, but rather only appears to require close-proximity paracrine communicaiton with feeders.